Example embodiments of the inventive concepts relate to a memory device including a massbit counter. For example, at least some example embodiments relate to a memory device including a massbit counter for precisely or roughly counting the number of off-cells according to a memory operation and/or a method of operating the memory device.
A semiconductor memory device is a memory device embodied by using a semiconductor such as silicon (Si), germanium (Ge), gallium arsenide (GaAs), or indium phosphide (InP). Semiconductor memory devices may be roughly classified into volatile memory devices and nonvolatile memory devices.
In particular, nonvolatile memory devices such as flash memory devices are used in various fields due to their high operating speed, low power consumption, low noise, and high capacity. In order to determine the program states of memory cells, a nonvolatile memory device may count the number of off-cells (or on-cells) from among the memory cells by using a desired (or, alternatively, a predetermined) verify voltage. A threshold voltage distribution shape of the memory cells and characteristics of the memory cells may be determined by using the counted number of the off-cells, and the nonvolatile memory device may perform a memory operation such as a program operation or a read operation based on the determined threshold voltage distribution shape and characteristics of the memory cells.
However, conventionally it may be difficult to vary the preciseness of the measurement of the threshold voltage distribution shape and characteristics of memory cells based on the specific memory operation.